The invention relates to a cleaning device for a bundle of tubular filter elements designed with one end open, preferably of an industrial dust filter, with injectors for delivery of a pulse-like compressed-air jet into the filter elements arranged opposite the openings of the filter elements, the compressed-air supply of the injectors, controlled via valves, taking place via a number of nozzle tubes extending at right angles to the injectors, and a number of injectors being connected in a row to each nozzle tube.
Such cleaning devices are used chiefly in industrial dust filters, as known from, for example, DE 44 40 279 A1. Filter elements such as e.g. filtering bags, fibrous filters or filtering tubes are distributed uniformly over the surface of a partition which separates the dusty-air space of the filter from its clean-air space. The filter elements project under their own weight into the dusty-air space arranged below, so that the dust-containing air flows through them from outside to inside. The filter elements are open at their upper end, so that they communicate with the clean-air space which is arranged above the partition and is operated at a lower pressure in relation to the dusty-air space.
Such filter elements have to be cleaned at intervals, as they become clogged from outside after a certain period of operation. A commonly used cleaning system consists in, in a reversal of the filtration direction, blowing compressed air in a pulse-like manner into the filter elements from the openings, as a result of which the dust or filter cake adhering on the outside can fly off and falls into a collecting unit arranged below the filter elements.
Especially great demands are made on the regeneration of the filter surfaces when the filter is used in production facilities with frequently changing products. In the case of such use of the filter, it is necessary to clean the entire dusty-air space including the filter elements thoroughly, in order that no product adulteration or product contamination can occur when a product change takes place. Such hygienically appropriate operation is essential above all in the processing of foods or pharmaceutical or medical products.
For generating the compressed-air pulse, injectors are arranged above the filter elements. As a rule, a number of injectors arranged in a row are supplied with the compressed air necessary for the cleaning operation via a common nozzle tube. The nozzle tube serving as a distributor can be connected to a compressed-air reservoir via a rapidly operable valve. By abrupt opening of the valve, compressed air passes into the nozzle tube and, via the injectors attached to the latter, into the filter elements from above. The control technology requirement associated with this is relatively great because, while a number of injectors are connected to the valve-controlled nozzle tube and can thus be operated simultaneously, each nozzle tube nevertheless has to be connected to the pressure reservoir via its own valve. The possibility of connecting all the nozzle tubes, which as a rule run parallel to one another, to a single, common valve and in this way reducing the control technology requirement, is rather of a theoretical nature. In practice, it turns out that, in this way, uniformly distributed pulse strength cannot be achieved in all injectors. Rather there is a risk that some injectors operate with higher pulse strength and other injectors with relatively lower pulse strength, which is not acceptable for uniform de-dusting of a filter.
The object of the invention is to produce a cleaning device for a bundle of tubular filter elements designed with one end open, which cleaning device works with a low control technology requirement and is to operate with uniformly distributed pulse strength of the injectors.